1. Field of the Invention
The present invention relates to a portable radio terminal apparatus for transmitting and receiving signals in different frequency ranges which includes an apparatus for switching the radio terminal apparatus over into a respective frequency range, a single antenna and a plurality of antenna matching circuits for matching the radio terminal apparatus to one of a number of frequency ranges.
2. Description of the Prior Art
Radio terminal apparatuses, and in particular radio terminal apparatuses that can be operated in different frequency ranges, are already known. These known radio terminal apparatuses are each equipped with either several antennas or several matching circuit arrangements for specific radio ranges. Such an apparatus is known from U.S. Pat. No. 4,989,230. The known apparatus is a telephone terminal apparatus for a private cordless telephone system and a public mobile radiotelephone system which comprises either two system-specific antennas or only one antenna. In the case of only one antenna, a lowpass filter is connected between this antenna and either a cordless telephone receiver circuit part, a cordless telephone transmitter circuit part. A high-pass filter is then connected between the antenna and either the mobile radiotelephone receiver circuit part or the mobile radiotelephone transmitter circuit part.
Radio apparatuses are also known, in particular for the shortwave region, that comprise an antenna with inserted blocking elements (e.g., inductances), so that antenna parts for particular frequency ranges can be switched effective or, respectively, ineffective.
In addition, stationary radio terminal apparatuses with broadband antennas are known whose relatively large mechanical dimensions turn out to be impracticable for portable radio terminal apparatuses.
The radio terminal apparatus according to the present invention is connected with a multiplicity of radio parts. Independent of the number of frequency ranges in which the inventive radio terminal apparatus can be operated, this apparatus includes only one antenna.
In an embodiment of the present invention, a portable radio terminal apparatus is provided which is capable of transmitting and receiving signals in different frequency ranges. The apparatus includes a switching device for switching the terminal apparatus between different frequency ranges; a single antenna to assist in the transmission and reception of the signals in different frequency ranges; a first antenna matching circuit connected to the antenna for matching the terminal apparatus to a first frequency range; and a plurality of additional antenna matching circuits, each of the plurality of additional antenna matching circuits being connected to the switching device and being individually connectable to the first antenna matching circuit via the switching device, wherein the switching device may connect any combination of the plurality of additional antenna matching circuits to the first antenna matching circuit for matching the terminal apparatus to a respective one of a plurality of frequency ranges.
In an embodiment, the portable radio terminal apparatus further includes a plurality of controllable switchover components in communication with the switching device, wherein each of the plurality of controllable switch over components is connected to one of the plurality of additional antenna matching circuits for enabling and disabling the connection of its respective antenna matching circuit to the first antenna matching circuit.
In an embodiment, the portable radio terminal apparatus includes PIN diodes as the plurality of controllable switchover components.
In an embodiment, the portable radio terminal apparatus further includes a frequency-range-determinative voltage signal produced by the switching device, wherein the voltage signal effects the connection of the plurality of additional antenna matching circuits to the first antenna matching circuit.
In an embodiment, the portable radio terminal apparatus further includes a frequency-range-determinative current signal produced by the switching device, wherein the current signal effects the connection of the plurality of additional antenna matching circuits to the first antenna matching circuit.
Additional features and advantages of the present invention are described in, and will be apparent from, the Detailed Description of the Preferred Embodiments and from the Drawings.